This invention relates generally to heat exchangers such as so-called charge air coolers for reducing the temperature of air inflow to a combustion engine. More specifically, this invention relates to an improved mounting arrangement for mounting a heat exchanger of the plate and fin type into the air intake manifold of a combustion engine for optimized heat transfer capacity.
Charge air cooler heat exchangers are well known in the art for mounting along the flow path of charge air supplied to a combustion engine. This charge air typically comprises ambient air which has been compressed by apparatus such as a supercharger or turbocharger to provide an increased mass flow of air to the engine to permit the engine to combust increased quantities of fuel and thereby operate at an increased level of power and performance. However, compression of ambient air also elevates the air temperature such that the charge air has a relatively high temperature which, if not reduced, undesirably increases total engine heat load. It is therefore desirable to cool the charge air prior to supply thereof to the engine, and charge air coolers are provided for this purpose.
In general, the charge air cooler is constructed from a plurality of lightweight heat transfer elements of a heat conductive material, such as copper or aluminum, shaped to provide extended heat transfer surfaces and defining a flow path for the charge air in heat transfer relation with a suitable coolant, such as ambient air or a liquid coolant. More specifically, the charge air cooler may be constructed from a network of finned tubes such that charge air flowing over the fins is associated with a coolant flowing through the tubes resulting in adequate heat transfer for some engine system applications. Alternatively, when improved heat transfer capacity is required, the charge air cooler is constructed from a stacked array of plates and fins which cooperate to define a heat exchanger core having separate flow paths for passage of the charge air and the coolant in close heat transfer relation with each other. In either case, however, the charge air cooler is desirably mounted directly into the intake manifold of the engine wherein charge air passing through the intake manifold is reduced in temperature by flow through the charge air cooler immediately prior to ingestion by the engine.
According to conventional installation techniques, the charge air cooler heat exchanger is mounted within the engine intake manifold by a plurality of bolts extending through opposite sides of the manifold and fastened into appropriate threaded structures on the charge air cooler. With tube-fin type heat exchangers, these threaded structures are normally formed by or mounted on support plates or baffles holding the tubes in spaced relation with each other, but special problems are encountered in providing such threaded structures in heat exchangers of the plate-fin type. More particularly, in the past, the threaded bolt-receiving structures have normally been mounted on the exterior of the heat exchanger where they occupy a substantial portion of the cross-sectional width of the intake manifold. As a result, the overall width of the heat exchanger must be reduced, with a corresponding reduction in total heat transfer capacity, to accommodate the threaded structures. Such reduction in the heat exchanger width unfortunately tends to create bypass flow paths for leakage of charge air around the heat exchanger which, if not closed, result in further reduced heat transfer capacity.
In some applications, it has been proposed to mount a plate-fin type charge air cooler heat exchanger into an engine intake manifold by use of elongated bolts passing entirely through the manifold and the heat exchanger and fastened with a nut located outside the manifold. This mounting technique advantageously permits the charge air cooler to assume an optimized width within the manifold for maximum heat transfer capacity and further eliminates and bypass leakage path around the heat exchanger. However, additional sealing structures are required to seal passage of the bolts through the heat exchanger core, and such sealing structures are particularly crucial when the coolant comprises a liquid coolant of the type circulated from a conventional engine cooling system. Unfortunately, the provision of sealing structures capable of withstanding the thermal stresses and thermal cycling during operation adds significantly to the cost and complexity of the heat exchanger.
There exists, therefore, a significant need for an improved yet relatively simple mounting arrangement for a plate-fin type charge air cooler heat exchanger which will permit the heat exchanger to occupy substantially the entire cross-sectional width of an engine intake manifold for optimum heat transfer capacity while avoiding use of elongated through-bolts and their attendant sealing structures. The present invention fulfills this need and provides further related advantages.